Regenerative blowers are generally used for transferring gas at a relatively low flow-rate and in a relatively high pressure, as in an industrial high-pressure blower (or a ring blower). Recently, the application range thereof is expanding to an air supply of a fuel cell system, a hydrogen recirculation system, and the like.
Such regenerative blowers are divided into an open channel type used as an air supply blower of a system requiring a low flow-rate and a high head and a side channel type. In the regenerative blower, blades are located in the circumferential direction of a disk-shaped rotary impeller. When the regenerative blower operates, internal circulation occurs between the recesses between the blades and the channels of a casing, thereby increasing pressure.
The regenerative blower must have a plurality of blades to raise the head. This consequently forms blade-passing frequencies (BPFs), i.e. high-frequency noise, and nose (overall noise). Although the noise of the regenerative blower can generally be reduced by reducing the number of revolutions by improving efficiency and relative performance, the noise reduction ability is limited.
In addition, when the regenerative blower is used for home and medical uses, a method of reducing noise using a muffler can be used. However, this method increases the cost and size of the regenerative blower and has a loss in flow rate of about 10% caused by the muffler.
Since the arrangement of the blades of the regenerative blower of the related art is controlled by a random number method, it is difficult to predict or adjust noise and efficiency based on the arrangement of the blades, which is problematic.
In addition, although the blades of the regenerative blower of the related art are arranged at unequal pitches by the random number method, the basis of the arrangement is insufficient and adjustment is difficult, which are problematic.